Musannaf Ibn Abi Shaybah 37373 — The words of Ibn Umar

It is narrated about Sayyiduna Ibn Umar (may Allah be pleased with them both) that he was travelling on the road to Makkah when he bent the head of his mount and said: "Perhaps a footprint may fall upon a footprint," meaning the footprint of the mount of the Prophet (peace and blessings be upon him).